The invention is based on a laminate for producing packaging containers as defined hereinafter. In a laminate of this type, known from European Patent application EP 0 144 011 B1, the inner layer and the outer layer in a longitudinal strip are not joined together, thus forming a channel. Also, perforations are formed in the inner laminate layer that is in contact with the product. Gas released by the packed product, such as carbon dioxide in the case of coffee, flows through the perforations into the channel when there is overpressure in the packaging container, and from there flows out into the open through openings at the ends of the channels into the edges of the top or bottom region of the package. A disadvantage of this laminate is that because of the relatively great length of the channel and because there are creases at the top and bottom and near the closure seams of the packaging container, which is embodied as a bag package, strains in the material engender choke points; because of these choke points, the opening pressure of the overpressure valve is set to be quite high. On the other hand, an overpressure that exceeds 10 mbar, for instance, inflates the bag package so much that it becomes unattractive, and some consumers might even suspect that the goods in it are spoiled.
To overcome this disadvantage, German Utility Model DE-GM 87 04 279 discloses providing perforations, through which the gas can escape, and which are offset from the perforations in the inner laminate layer, in the outer laminate layer as well. This makes for short paths for the gas and hence a lower opening pressure. Nevertheless, in such bag packages it can happen that if the package walls are deformed, the channels will be compressed as a result of strains. This means that safe and reliable escape of the gas is no longer assured.